<div class="container">
    <div class="col-md-12">
        <form action="" method="POST" role="form">
            <legend>
                Login
            </legend>
            <div class="form-group">
                <label for="">
                    用户名
                </label>
                <input class="form-control" name="username" placeholder="请输入用户名" type="text" value="admin">
                </input>
            </div> 
            <div class="form-group">
                <label for="">
                    密码
                </label>
                <input class="form-control" name="password" placeholder="请输入密码" type="password" value="chenjia@2021">
                </input>
            </div>
            <div class="pull-right"><button class="btn btn-primary" type="submit">
                登录
            </button></div>
        </form>
    </div>
</div>